Add Job Event Messaging to tasks.

* Added test for sample and cleanup

* Added skipEventsListener

* Added new message format.

* Added integration tests.

* Updated application.properties to add json content type

resolves spring-cloud/spring-cloud-task#119

spring-cloud-task-samples/pom.xml

@@ -28,6 +28,7 @@
 		<module>taskprocessor</module>
 		<module>partitioned-batch-job</module>
 		<module>task-events</module>
+		<module>batch-events</module>
 	</modules>
 
 	<build>